Brand Names: U.S.

LamISIL

Terbinex [DSC]

Pharmacologic Category

Antifungal Agent, Oral

Pharmacology

Synthetic allylamine derivative which inhibits squalene epoxidase, a key enzyme in sterol biosynthesis in fungi. This results in a deficiency in ergosterol within the fungal cell wall and results in fungal cell death.

Tinea corporis/tinea cruris

Data from a double-blind, randomized clinical study suggest that oral terbinafine may be effective in the treatment of widespread tinea corporis/tinea cruris [Del Palacio Hernanz 1990]. Additional data may be necessary to further define the role of oral terbinafine in this condition.

Tinea pedis/manuum

Data from a double-blind, randomized phase III study support the use of oral terbinafine in the treatment of tinea pedis [Tausch 1998].

Contraindications

Hypersensitivity to terbinafine or any component of the formulation; chronic or active hepatic disease

Dosing: Adult

Note: Lamisil granules have been discontinued in the United States for more than 1 year.

Dosing: Renal Impairment

There are no dosage adjustments provided in the manufacturer's labeling (has not been studied); however, clearance is decreased 50% in patients with CrCl ≤50 mL/minute.

Dosing: Hepatic Impairment

Contraindicated in chronic or active hepatic disease.

Extemporaneously Prepared

A 25 mg/mL oral suspension may be made using tablets. Crush twenty 250 mg tablets and reduce to a fine powder. Add small amount of a 1:1 mixture of Ora-Sweet® and Ora-Plus® and mix to a uniform paste; mix while adding the vehicle in geometric proportions to almost 200 mL; transfer to a calibrated bottle, rinse mortar with vehicle, and add quantity of vehicle sufficient to make 200 mL. Label "shake well" and "refrigerate". Stable 42 days.

Administration

Administer tablets without regard to meals. Administer granules with food; sprinkle granules on a spoonful of pudding or other soft, nonacidic food (eg, mashed potatoes); swallow entire spoonful without chewing; do not mix granules with applesauce or other fruit-based foods.

ARIPiprazole: CYP2D6 Inhibitors (Moderate) may increase the serum concentration of ARIPiprazole. Management: Monitor for increased aripiprazole pharmacologic effects. Aripiprazole dose adjustments may or may not be required based on concomitant therapy and/or indication. Consult full interaction monograph for specific recommendations. Monitor therapy

Brexpiprazole: CYP2D6 Inhibitors (Moderate) may increase the serum concentration of Brexpiprazole. Management: If brexpiprazole is to be used together with both a moderate CYP2D6 inhibitor and a strong or moderate CYP3A4 inhibitor, the brexpiprazole dose should be reduced to 25% of the usual dose. Monitor therapy

Codeine: CYP2D6 Inhibitors (Moderate) may diminish the therapeutic effect of Codeine. These CYP2D6 inhibitors may prevent the metabolic conversion of codeine to its active metabolite morphine. Monitor therapy

Metoprolol: CYP2D6 Inhibitors may increase the serum concentration of Metoprolol. Management: Consider an alternative for one of the interacting drugs in order to avoid metoprolol toxicity. If the combination must be used, monitor response to metoprolol closely. Metoprolol dose reductions may be necessary. Consider therapy modification

TraMADol: CYP2D6 Inhibitors (Moderate) may diminish the therapeutic effect of TraMADol. These CYP2D6 inhibitors may prevent the metabolic conversion of tramadol to its active metabolite that accounts for much of its opioid-like effects. Monitor therapy

• Gastrointestinal effects: Taste disturbance (including loss of taste) may occur and severe cases resulting in decreased food intake, weight loss, anxiety or depression have been reported; resolution may be delayed (eg, several weeks to >1 year) following discontinuation of therapy or in some cases, disturbance may be permanent. Discontinue therapy in patients with symptoms of taste disturbance.

• Hematologic effects: Transient decreases in absolute lymphocyte counts were observed in clinical trials; severe neutropenia (reversible upon discontinuation) has also been reported. Monitor CBC in patients with preexisting immunosuppression if therapy is to continue >6 weeks. Discontinue therapy if ANC ≤1,000/mm3.

• Hepatic failure: Cases of hepatic failure, some leading to liver transplant or death, have been reported. May occur in patients with and without preexisting hepatic disease; severity of hepatic events and/or outcomes may be worse in patients with active or chronic hepatic disease. Perform baseline and periodic liver function tests; discontinue use if clinical evidence of liver injury develops (eg, nausea, anorexia, fatigue, vomiting, right upper abdominal pain, jaundice, dark urine, pale stools) or elevated liver function tests occur.

• Ocular effects: Although rare, changes in the ocular lens and retina have been reported; discontinuation of therapy may be required.

• Respiratory effects: Smell disturbance (including loss of smell) has been reported; resolution may be delayed (eg, >1 year) following discontinuation of therapy or in some cases, disturbance may be permanent. Discontinue therapy in patients with symptoms of smell disturbance.

Monitoring Parameters

Pregnancy Risk Factor

B

Pregnancy Considerations

Adverse events were not observed in animal reproduction studies. Avoid use in pregnancy since treatment of onychomycosis is postponable.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.